Temporary repair device for mechanical drive couplings

ABSTRACT

A repair device for a flexible drive coupling having a shell and a hub includes a first member fixed to the shell and a second member fixed to the hub. The first member includes a slot. A portion of the second member extends from the hub and is slidably positioned within the slot. The first and second members are drivingly engageable with one another to transfer torque between the shell and the hub while allowing the hub and shell to move relative to one another.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to mechanical drive couplings and, moreparticularly, to a temporary repair device for mechanical drivecouplings.

Mechanical drive couplings are often used to provide a drivingconnection between power supplies such as a motor and mechanisms to bedriven, such as a pump, a gear reduction unit or the like. Based on thedifficulty of exactly aligning the components of such systems, flexibledrive couplings are used to accommodate reasonable degrees ofnon-alignment between the shaft members of the power source and thedriven component.

One type of flexible drive coupling includes a rigid half and a flexiblehalf. The flexible half is fixed to either the driving or driven shaftand rotates about the centerline of the shaft to which it is connected.The flexible half is a two-part assembly including a coupling shell anda coupling hub. The coupling shell is fixed to the rigid half. Thecoupling hub includes external gear elements which mesh with internalgear elements of the coupling shell. The coupling hub may move withinthe coupling shell to accommodate for misalignment between the drivingand driven shafts while maintaining a rotary power interconnectionbetween the rigid half and the flexible half.

While these gear type flexible drive couplings have performedsufficiently in the past, concerns arise. Specifically, the gearinterface between the coupling hub and the coupling shell sometimesfails. The failure is usually due to friction created from excessivemisalignment, lack of lubrication or both. When the coupling fails, thegear segments of the hub slide past the gear segments of the shell. Assuch, torque is not transmitted through the flexible drive coupling.Once the coupling no longer transmits torque, the alternatives availableinclude replacing the coupling or making a temporary repair to theexisting coupling. Unfortunately, a new coupling is often not availabledue to the variety of coupling types and sizes used. Furthermore, thecost of maintaining a complete selection of service stock isprohibitive. Therefore, it would be advantageous to repair the existingcoupling in order to be able to minimize down time and use the machinerywhile waiting for a replacement coupling to arrive.

Several repair methods have been attempted. One method includes weldingthe shell to the hub. This repair eliminates any flexibility in thejoint and usually fails within a very short period of time. Anotherrepair method includes burning a hole through the shell and welding apost to both the hub and the shell. This repair typically does notperform well and suffers repeated breakdowns.

Accordingly, it is an object of the present invention to provide atemporary repair device for a flexible drive coupling which is durableand capable of maintaining relative movement between the coupling huband the coupling shell.

It is a further object of the present invention to provide a temporaryrepair device for a flexible drive coupling that may be installed on afailed drive coupling without disassembling the components which aredrivingly interconnected.

It is another object of the present invention to provide a repair devicefor a flexible drive coupling which is economical to stock ormanufacture and easy to install.

Therefore, the present invention includes a temporary repair device fora flexible drive coupling having a shell and a hub. The repair deviceincludes a first member fixed to the shell and a second member fixed tothe hub. The first member includes a slot. A portion of the secondmember extends from the hub and is slidably positioned within the slot.The first and second members are drivingly engageable with one anotherto transfer torque between the shell and the hub while allowing the huband shell to move relative to one another while rotating about axeswhich are not coaxially aligned.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a fragmentary perspective view of an exemplary flexible drivecoupling equipped with a temporary repair device constructed inaccordance with the teachings of the present invention;

FIG. 2 is a partial cross-sectional side view of the flexible drivecoupling and temporary repair device of the FIG. 1;

FIG. 3 is a perspective view of an alternate embodiment temporary repairdevice;

FIG. 4 is a side view of the alternate embodiment temporary repairdevice of FIG. 3 coupled to an exemplary flexible drive coupling;

FIG. 5 is a top view of a first member of the temporary repair device;

FIG. 6 is a plan view of the first member of the temporary repairdevice;

FIG. 7 is an end view of an alternate embodiment temporary repair devicecoupled to a flexible drive coupling of a predetermined size;

FIG. 8 is an end view of an alternate embodiment temporary repair devicecoupled to an exemplary flexible drive coupling having a size greaterthan the drive coupling of FIG. 7;

FIG. 9 is an end view of another alternate embodiment temporary repairdevice shown coupled to a flexible drive coupling having a size greaterthan the drive couplings shown in FIGS. 7 and 8;

FIG. 10 is a side view of an alternate embodiment temporary repairdevice shown coupled to a shrouded flexible drive coupling;

FIG. 11 is a perspective view of the temporary repair device andshrouded coupling of FIG. 10;

FIG. 12 is a top view of a first member of the alternate embodimenttemporary repair device of FIG. 10;

FIG. 13 is a side view of the first member of the alternate embodimentrepair device; and

FIG. 14 is a front view of the first member of the alternate embodimenttemporary repair device of FIGS. 10 and 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

FIGS. 1 and 2 depict an exemplary flexible drive coupling 8 having atemporary repair device 10 coupled thereto. Drive coupling 8 includes arigid half 12 and a flexible half 14 interconnected by a plurality ofthreaded fasteners 16. Rigid half 12 includes a generally cylindricalbody 18 having a flange 20 radially extending therefrom. Flange 20includes a plurality of apertures 22 for receipt of threaded fasteners16. A bore 24 extends axially through body 18. Bore 24 is sized forreceipt of a first shaft 26. First shaft 26 is positioned within bore 24and drivingly coupled to rigid half 12 via a drive key or other standardshaft fastening device, not shown. A recess 28 extends inwardly from amounting face 30 of flange 20. Recess 28 is in communication with bore24.

Flexible half 14 includes a shell 32 and hub 34. Hub 34 is drivinglyinterconnected to shell 32 such that torque provided from first shaft 26is transferred to a second shaft 36. Torque is transferred from firstshaft 26 through rigid half 12 to shell 32 of flexible half 14. Thetorsional load path continues to flow from shell 32 to hub 34. However,hub 34 is free to axially translate and pivot a predetermined amountrelative to shell 32. Accordingly, a misalignment between first shaft 26and a second shaft 36 is accommodated. Second shaft 36 is drivinglycoupled to hub 34 via a key or other fastener not shown.

Shell 32 includes a substantially cylindrical hollow body 38 having anouter surface 39 and a flange 40 radially extending therefrom. Flange 40includes a mounting face 42 in engagement with mounting face 30 of rigidhalf 12. A plurality of apertures 44 extend through flange 40. Apertures44 are aligned with apertures 22 and are in receipt of threadedfasteners 16. A lip 46 inwardly extends from body 38 and includes an endface 48. A plurality of circumferentially spaced protrusions or gears 50extend inwardly from body 38. An annular groove 52 is positioned betweenlip 46 and gears 50. A seal 54 is positioned within groove 52 betweenhub 34 and shell 32. Seal 54 is preferably constructed from acompressible elastomeric material. Shell 32 also includes a counter bore56 inwardly extending from mounting face 42. A portion of counter bore56 is similarly sized and aligned with recess 28 of rigid half 12.

Hub 34 includes a substantially cylindrical body 58 having a first endface 60, a second end face 62 and a bore 64 axially extending from firstend face 60 to second end face 62. When assembled within shell 32, firstend face 60 is axially offset from end face 48 of shell 32. A pluralityof protrusions or gears 66 extend radially outwardly from an externalsurface 67 of body 58. Gears 66 of hub 34 engage gears 50 of shell 32 toform a plurality of interfaces where torsional energy may betransferred. One skilled in the art will appreciate that gears 66 arefree to axially translate relative to shell 32 a distance defined by theclearance between second end face 62 of hub 34 and a land 68 of recess28. Furthermore, a radial clearance exists between protrusions 66 andprotrusions 50 such that hub 34 may rotate about an axis transverse to alongitudinal axis 69 of second shaft 36. Accordingly, misalignmentbetween longitudinal axis 69 of second shaft 36 and a longitudinal axis71 of first shaft 26 is tolerated.

When gears 66 of hub 34 are no longer capable of transmitting torque togears 50 of shell 32, a need for repair device 10 arises. Repair device10 includes a first member 70 fixed to shell 32 and a second member 72fixed to hub 34. First member 70 is drivingly coupled to second member72 to provide a torque transfer path from shell 32 to hub 34. The firstand second members are interconnected to allow hub 34 to axiallytranslate and/or pivot relative to shell 32 as initially designed.Because repair device 10 provides a flexible drive interconnection, therepair to flexible drive coupling 8 has a service life greater thanpreviously known repairs. Additionally, first member 70 and secondmember 72 are coupled to flexible drive coupling 8 without dismantlingthe drive coupling or any adjacent components. Therefore, repair device10 may be installed in a very short period of time.

FIGS. 1 and 2 depict a single first member 70 and a single second member72 interconnected with one another to form repair device 10. Inpractice, multiple first members 70 and second members 72 may becircumferentially spaced about flexible drive coupling 8 in meshed pairsas shown in FIGS. 3, 4 and 7-9. The use of multiple meshed pairs assuresa desired torque capacity is met. Depending on the size of the flexiblecoupling, virtually any number of meshed pairs may be used. However, ithas been found to be advantageous to use four meshed pairs on a flexibledrive coupling having a shell outer diameter under 8 inches. Six meshedpairs equally spaced from one another have been found to perform well ondriving couplings having a shell outer diameter ranging from 8 to 19inches. Eight meshed pairs of first and second members have been founduseful to transfer torque on a flexible coupling having a shell outerdiameter of 20 to 28 inches. Twelve meshed pairs may be used for shellshaving an outer diameter of 29 inches or more. It should also beappreciated that the arc length spanned by each first member 70 and thewidth of each second member 72 may be varied according to the torquetransfer requirements and the number of meshed pairs being used on anygiven flexible drive coupling.

FIGS. 5 and 6 depict first member 70 in greater detail. First member 70is shaped as a section of a cylindrical tube. First member 70 includesan inner arcuate wall 74 and an outer arcuate wall 76 extending from afirst side wall 78 to a second side wall 80. While the wall 74 isdemonstrated as being arcuate, as shall be appreciated by those skilledin the art, the wall may have other configurations. First member 70includes a first end face 82 and a second end face 84. A slot 86 extendsinwardly from second end face 84 and terminates at a curved wall 88. Acurved shape is used to minimize stress concentrations formed at thebase of slot 86. Slot 86 includes substantially parallel walls 90 spacedapart from one another a predetermined distance 92. Distance 92 isdefined to be slightly larger than a width 94 (FIG. 3) of second member72. Accordingly, second member 72 is free to move axially relative tofirst member 70 but is restrained from relative rotational movement.

Second member 72 is an elongated member having a substantiallyrectangular cross-section. Second member 72 includes a mounting face 96fixed to first end face 60 of hub 34. Second member 72 further includesa pair of substantially parallel and spaced apart side walls 98. Sidewalls 98 are spaced apart a distance less than distance 92 to providethe slip-fit previously described.

A first end 100 of second member 72 radially extends beyond outersurface 39 of shell 32 and is positioned within slot 86. Second member72 includes a second end 102 opposite first end 100. Second end 102 maybe positioned in contact with second shaft 36 or may be spaced aparttherefrom. However, it should be appreciate that second member 72 ispreferably not welded to the second shaft 36 to preserve its integrity.It is contemplated that when a replacement flexible drive couplingarrives at the manufacturing location, temporary repair device 10 andthe original failed coupling are removed from the driving and drivendevices without damage to first shaft 26 and second shaft 36. Therefore,additional repair to the driving and driven components is easilyavoided.

FIGS. 10-14 depict an alternate embodiment repair device 200 for usewith a shrouded coupling 202. Shrouded coupling 202 is substantiallysimilar to flexible drive coupling 8 previously introduced. Accordingly,like elements will retain their previously introduced referencenumerals. Shrouded coupling 202 includes a shell 204 having asubstantially cylindrical body 206. Body 206 is hollow and has a wallsection substantially thicker than the wall section of body 38. Theincreased wall section is internally stepped to shield the gearinterface of shell 204 to a stepped hub 208. The thicker wall section ofshell 204 results in body 206 having an end face 210 of increased size.Based on the increased size of end face 210, a first member 212 ofrepair device 200 is constructed to include an “L” shaped section.

First member 212 includes a first leg 214 and a second leg 216substantially orthogonally intersecting one another. First leg 214includes an inner arcuate surface 218 and an outer arcuate surface 220.Second leg 216 includes a offset inner arcuate surface 222. A slot 224extends through first leg 214 and second leg 216. Slot 224 includesfirst and second side walls 226 selectively engageable with a secondmember 228. As previously described, second member 228 is sized toslip-fit within slot 224 of first member 212. Second leg 216 includes astop face 230 in engagement with end face 210. It should be appreciatedthat second leg 216 radially inwardly extends across end face 210 butdoes not contact hub 208 of shrouded coupling 202.

To assemble repair device 200 to shrouded coupling 202, first member 212is mounted to shell 204. Preferably, first member 212 is welded to shell204. A portion of second member 228 is positioned within slot 224.Second member 228 is mounted on an end face 232 of hub 208. Preferably,second member 228 is welded to hub 208. Therefore, repair device 200allows power to be transferred between shell 204 and hub 208 while shell204 rotates about an axis not aligned with the rotational axis of hub208.

Furthermore, the foregoing discussion discloses and describes merelyexemplary embodiments of the present invention. One skilled in the artwill readily recognize from such discussion, and from the accompanyingdrawings and claims, that various changes, modifications and variationsmay be made therein without department from the spirit and scope of theinvention as defined in the following claims. For example, FIGS. 10 and11 show two meshed pairs of first and second members. However, virtuallyany number of meshed pairs may define the repair device.

1. A repair device for a flexible drive coupling having a shell and ahub, the repair device comprising: a first member fixed to the shell,the first member including a slot; and a second member fixed to the hub,a portion of said second member extending from the hub, said portionbeing slidably positioned within said slot, said first member beingdrivingly engageable with said second member to transfer torque betweenthe shell and the hub while allowing the hub and shell to move relativeto one another.
 2. The repair device of claim 1 wherein the shell isrotatable about a first axis and the hub is rotatable about a secondaxis misaligned with said first axis, said first member being rotatableabout said first axis, said second member being rotatable about saidsecond axis.
 3. The repair device of claim 2 wherein said first memberincludes a bifurcated end in receipt of said portion of said secondmember.
 4. The repair device of claim 1 wherein said first memberincludes & an arcuate inner wall engaging an outer surface of the shell.5. The repair device of claim 4 wherein said first member includes anarcuate outer wall extending substantially parallel to said arcuateinner wall.
 6. The repair device of claim 5 wherein said arcuate innerwall and said arcuate outer wall extend for an arc lengths substantiallyless than forty-five degrees.
 7. The repair device of claim 1 furtherincluding third, fourth, fifth and sixth members, said third and fifthmembers being substantially similar to said first member and beingcircumferentially spaced apart from one another and fixed to the shell,said fourth and sixth members being substantially similar to said secondmember and being circumferentially spaced apart from one another andfixed to the hub, said third member slidably engaging a slot of saidfourth member and said fifth member slidably engaging a slot of saidsixth member.
 8. The repair device of claim 2 wherein said slot of saidfirst member extends in a direction substantially parallel to said firstaxis.
 9. The repair device of claim 8 wherein said second member extendsin a direction substantially perpendicular to said second axis.
 10. Therepair device of claim 9 wherein said slot Is formed in a bifurcated endof said first member.
 11. The repair device of claim 1 wherein saidfirst member includes a first leg engaging an outer cylindrical surfaceof the shell.
 12. The repair device of claim 11 wherein said firstmember includes a second leg extending orthogonally from said first leg,said second leg including said slot.
 13. A method for repairing aflexible drive coupling having a shell and hub, the shell being coupledto a first shaft and rotatable about a first axis, the hub being coupledto a second shaft and rotatable about a second axis misaligned from thefirst axis, the method comprising: mounting a first member to the shell,said first member including a slot; slidably positioning a portion of asecond member within said slot; and mounting said second member to thehub, wherein rotation of the shell drivably engages the first and secondmembers to cause the hub to rotate.
 14. The method of claim 13 furtherincluding extending a first end of said first member from the shell. 15.The method of claim 14 further including extending said portion of saidsecond member from the hub, wherein said portion is moveable within saidslot while torque is being transferred between said first and secondmembers.
 16. The method of claim 15 wherein said first end of said firstmember is bifurcated.
 17. The method of claim 16 further includingwelding a second end of said first member to the shell.
 18. The methodof claim 17 further including welding said second member to the hub. 19.The method of claim 13 further including mounting a third member to theshell, said third member including a slot; slidably positioning aportion of a fourth member in said slot of said third member; andmounting said fourth member to the hub.
 20. The method of claim 19wherein said first and third members are circumferentially spaced apartfrom one another.
 21. The method of claim 13 further including engagingan inner arcuate surface of said first member with an outer surface ofthe shell.
 22. The method of claim 21 further including engaging saidfirst member with an end face of the shell.
 23. A method of repairing aflexible drive coupling having a shell and a hub, the shell beingrotatable about a first axis and the hub being rotatable about a secondaxis not aligned with the first axis, the method comprising: mounting afirst member to the shell; mounting a second member to the hub; anddrivingly interconnecting said first and second members to provide atorque transfer path between the shell and the hub.
 24. The method ofclaim 23 further including engaging a portion of said second member withsaid first member.
 25. The method of claim 24 further including slidablypositioning said portion of said second member within a slot formed insaid first member.
 26. The method of claim 26 further includingpositioning said slot to extend in a direction substantially parallel tothe first axis.
 27. The method of claim 27 further including positioningsaid second member to extend in a direction substantially perpendicularto the second axis.